I think the Libs/Nats are generally more conservative so a greater proportion of their voters would prefer the status quo. Me, I want to see a Republic but was against the "popularly elected" model as it would just create another election and another politician. I am all for a minimalist model where Parliament chooses the President and the Pres's role is exactly the same as what the G-G does today.
But I don't see this as an urgent or pressing need. We had our chance to change and because of the division in the republican camp, we blew it. Maybe in 20 years time.
